ECOPHYSIOLOGICAL ASPECTS OF FORAGE MANAGEMENT AND ITS IMPLICATIONS FOR IPM AT THE FARMSCAPE LEVEL

There is growing recognition that biodiversity contributes to the ecological stability, resilience, and sustainability on farms. Farm biodiversity includes not only all forms of life, but it also includes their often beneficial ecological functions. Examples of arthropod biodiversity of value to producers include native bees that increase pollination of crops, decomposers that help to break down plant and animal debris on the land, insects as food for desirable vertebrates, and natural enemies that attack and kill pest species. Here, I propose to document the value of perennial forage crops as a source of beneficial biodiversity on farmscapes, with a focus on generalist insect natural enemies (i.e., predators). These natural enemies not only help reduce pests in alfalfa (e.g., alfalfa weevil, leafhoppers, caterpillars, aphids), but they also disperse to other areas of the farm where they kill pests on other crops as well. In addition to this research, I will continue my interdisciplinary research and teaching collaborations through NCCC-31.In recent years, ecological intensification has been suggested as a means to better meet our growing agricultural needs while reducing inputs and enhancing ecosystem services of value to crop and pest management. Intensification is accomplished by supporting the natural ecosystem processes to the benefit of agriculture. For example, producers can time pesticide applications and harvest dates to benefit species that provide regulating services such as pest management. For the research described under Objective 1, I focus on the use and management of forage crops, with an emphasis on alfalfa, to document the key species of natural enemies in the farmscape that critically utilize forage crops during their life cycle. I intend to quantify the production of natural enemies dispersing from forage crops, and determine methods to manage forage crops to enhance natural enemy populations.Entomologists have long observed the high number of species of insects and related forms of arthropods in alfalfa fields. A high proportion of these species are natural enemies, often responsible for killing insect pests. Ecophysiological aspects of alfalfa and other forage crops provide unique habitat conditions for many natural enemies. While the perennial habit of forages provides long periods without disturbance (e.g., October-April), frequent disturbance during the summer growing season can be detrimental to their populations. Despite the large number of beneficial species inhabiting alfalfa, the crop system can enhance biodiversity at the farmscape level only if it serves as habitat for the beneficial species to reproduce. Documentation of rates of reproduction of beneficial species is missing from the literature. For example, forage entomologists are familiar with the response of natural enemies of pea aphids during the spring of each year: rapid reproduction of aphids attracts natural enemies that oviposit on alfalfa plants, and whose larvae consume aphids. These larvae then become adults that can disperse to other crops on the farm before first harvest to serve as predators and parasites of pests. Some species are associated with foliage, while others are associated with soil.The production of alfalfa on farms may promote beneficial biodiversity on farms overall through increased reproduction of natural enemies. Alfalfa may be an excellent means to improve beneficial biodiversity, thus reducing pest loads on multiple crops on farms while still providing high quality forage for animals. To test this hypothesis, I propose to first collect data to estimate the abundance and rate of reproduction of generalist natural enemies within alfalfa fields. In addition, I will monitor the movement of natural enemies out of alfalfa fields. Furthermore, I will use degree-day data, generated by my lab or found in the literature, to estimate the impact of alfalfa harvest schedules on generalist predators. Degree-days, which is a measure of heat accumulation over time, provide estimates of insect developmental time. In addition, I will survey those species that have larval stages in the soil to determine how general management practices (e.g., pesticide applications, fertilization, harvesting) may affect their reproduction. Although this part of the project only includes Maryland, I intend to develop data to demonstrate the potential for enhancing beneficial biodiversity and develop standardized means to measure natural enemy reproduction in other areas of the country.I have been active in the Multi-State Project, NCCC-31, "Ecophysiological Aspects of Forage Management" since 2007. This is a multidisciplinary project that includes agronomists, plant breeders, animal scientists, extension specialists, crop physiologists, etc. As an entomologist, my interactions within NCCC-31 have included the sharing of information on pest and beneficial arthropods found in forage crops, providing data for multistate research projects, and leading in externally-funded projects on issues related to forage crop management. In addition, I collaborate with members of NCCC-31 in the development and writing of books and book chapters, focused on both students as well as forage professionals. I intend to continue those interactions in the future, and therefore two of the objectives below are exactly as worded in the NCCC-31 description on NIMMS.The overall goal of my lab's biodiversity research is to locate habitats that can increase beneficial arthropods in the farmscape, and develop management practices that help to conserve or augment the populations of natural enemies. Here, I focus on forage crops as a source of generalist natural enemies. In addition, I work closely with other members of the forage research and extension community in the United States to share information and collaborate on current research and education activities.My research and education objectives are:To conduct research to identify key species of natural enemies at the farmscape level, and quantify their production within forage crop systems with an emphasis on alfalfa.To identify emerging forage-related issues and develop collaborative efforts that address high priority physiological, ecological, and management challenges and opportunities.To develop innovative and effective educational and outreach programs that meet regionally broad stakeholder needs related to forage and grassland management.